1. Field of the Invention
The present invention relates to an optical disk drive apparatus and an optical pickup for irradiating a recording medium (or storage medium), in the form of an optical disk such as a compact disk (CD), a digital versatile disk (DVD) or in the form of a magneto-optical disk such as a mini disk (MD), with a light beam to perform optical processing (e.g. reading or writing of data). The present invention also relates to a method for manufacturing an optical disk drive apparatus or an optical pickup and a method for adjusting an optical disk drive apparatus or an optical pickup.
2. Description of the Related Art
Generally, in an optical disk drive apparatus, the quality of a recording signal directed to an optical disk (i.e. a recording medium, which will be sometimes referred to simply as a “disk” hereinafter) and the quality of a reproduction signal produced from the disk is greatly affected by the degree of perpendicularity (or skew) of the optical pickup relative to the irradiated surface (e.g. the recording surface side or its reverse side) of the disk to which an optical beam is directed. In view of this fact, it has been proposed, as disclosed in Japanese Patent Application Laid-Open No. 11-306548, to provide a skew adjustment mechanism in the optical disk drive so as to adjust the skew by means of the skew adjustment mechanism provided in the optical disk drive upon mounting an optical pickup on the optical disk drive so that a required degree of perpendicularity would be obtained.
Specifically, an example of a conventional optical disk drive apparatus is shown in FIG. 11, in which a tray 2 on which a disk 1 is to be placed is mounted on a main chassis 3 in such a way as to be capable of being loaded into and unloaded from the main chassis 3 in the direction designated by a double sided arrow A-B in FIG. 11, by means of a loading/unloading mechanism (not shown). In the main chassis 3, there is also provided a mechanical unit 5 including mechanical chassis 4 on which a disk recording and reproducing mechanism and other mechanisms are packaged or mounted.
On the mechanical chassis 4, there is mounted a disk motor (or a spindle motor) 6, an optical pickup 7 and an optical pickup feed (or advancing) mechanism 8 for moving the optical pickup 7 in the tracking direction. A turntable 9 on which a disk 1 is placed so as to be rotated is mounted on an output shaft of the disk motor 6.
The optical pickup 7 is supported on a main shaft 10 and a sub-shaft 11 serving as two guide shafts mounted on the mechanical chassis 4 via a skew adjustment mechanism. The optical pickup 7 is movable relative to the main shaft 10 and the sub-shaft 11, that is, relative to the mechanical chassis, in the axial direction (which coincides with the tracking direction) of the main shaft 10 and the sub-shaft 11.
In the following, the skew adjustment mechanism in the conventional apparatus will be described with reference to FIGS. 11 and 12.
As shown in FIGS. 11 and 12, the main shaft 10 is supported on the mechanical chassis 4 via an inclination adjustment fulcrum 10A near one end thereof and via an inclination adjustment point 10B near the other end thereof. On the other hand, the sub-shaft 11 is supported on the mechanical chassis 4 via an inclination adjustment point 11A near one end thereof and via an inclination adjustment point 11B near the other end thereof.
The inclination adjustment fulcrum 10A is adapted to support the main shaft 10 in such a way that the main shaft 10 is pivotable in a direction perpendicular to the plane of the sheet of FIG. 11. The inclination adjustment point 10B is adapted to support the main shaft 10 via a height adjustment mechanism 12 in the form of a screw mechanism, a cam mechanism or the like so as to be capable of adjusting the position with respect to the height direction (see FIGS. 11 and 12) of the main shaft 10 near the inclination adjustment point 10B, relative to the mechanical chassis 4.
On the other hand, the inclination adjustment points 11A and 11B are adapted to support the sub-shaft 11 via height adjustment mechanisms 13A and 13B in the form of screw mechanisms, cam mechanisms or the like so as to be capable of adjusting the position with respect to the height direction of the sub-shaft 11 near the inclination adjustment points 11A and 11B, relative to the mechanical chassis 4.
In the above described apparatus, skew adjustment in the tangential direction shown in FIG. 12 (that is, adjustment of inclination of the optical axis with respect to the disk surface as seen from the moving trajectory direction (i.e. tracking direction) of a light spot (or an objective lens 15) on the disk surface) is attained by operating the height adjustment mechanism 13A at the inclination adjustment point 11A and the height adjustment mechanism 13B at the inclination adjustment point 11B of the sub-shaft by the same shift amount, in the same direction.
On the other hand skew adjustment in the radial direction shown in FIG. 12 (that is, adjustment of inclination of the optical axis with respect to the disk surface as seen from the direction orthogonal to the moving trajectory direction of a light spot on the disk surface) is attained by operating the height adjustment mechanism 12 at the inclination adjustment point 10B of the main shaft 10 and the height adjustment mechanism 13B at the inclination adjustment point 11B of the sub-shaft by the same shift amount, in the same direction.
In the conventional apparatus in which the skew adjustment is performed by means of the skew adjustment mechanism as disclosed in Japanese Patent Application Laid-Open No. 11-306548, in the case in which relatively large skew adjustment is required, the distance between the objective lens 15 and the lower surface of the disk 1 greatly varies between the inner portion and the outer portion of the disk 1. So it is necessary to provide a large movable range for a movable portion 17 of an actuator 16 for moving the objective lens 15 in the height direction, in order to allow adequate adjustment (i.e. focus adjustment) of the distance (i.e. working distance W.D.) between the objective lens 15 and the lower surface of the disk 1 and to cope with surface runout (or wobbling) of the disk 1, as shown in FIG. 13.
Consequently, it is necessary to make the dimension of the movable portion 17 and the actuator large in the height direction, and that the dimension of the optical pickup 110 becomes necessarily large. So it is difficult to reduce the size and weight of the optical disk drive apparatus.
Furthermore, since the above-described conventional apparatus uses various mechanisms such as mechanisms for adjusting the heights of the height adjustment points 10B, 11A and 11B of the main shaft 10 and the sub-shaft 11, the number of parts becomes large and the structure of the apparatus becomes complex. In addition, the skew adjusting operation, which requires mechanical adjustment, is also complicated. Therefore it is actually difficult to achieve size reduction, improvement in productivity and cost reduction of the optical disk drive apparatus.